Implantable vascular device

ABSTRACT

A multiple-sided medical device comprises a frame comprising wire or other resilient material and having a series of bends and interconnecting sides. The device has both a flat configuration and a second, folded configuration which a generally serpentine shape. The device is pushed from a delivery catheter into the lumen of a duct or vessel and may include one or more barbs for anchoring purposes. A full or partial covering of fabric or other flexible material such as DACRON, PTFE, or a collagen-based material such as small intestinal submucosa (SIS), may be sutured or attached to the frame using heat or pressure welding crimping, adhesive, or other techniques to form an occlusion device, a stent graft, or an implantable, intraluminal valve such as for correcting incompetent veins in the lower legs and feet.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of provisional application Ser.No. 60/180,002, filed Feb. 3, 2000 and regular utility application Ser.No. 09/324,382, filed Jun. 2, 1999.

Technical Field

[0002] This invention relates to medical devices, more particularly, tointraluminal devices.

BACKGROUND OF THE INVENTION

[0003] As minimally invasive techniques and instruments for placement ofintraluminal devices have developed over recent years, the number andtypes of treatment devices have proliferated as well. Stents, stentgrafts, occlusion devices, artificial valves, shunts, etc., haveprovided successful treatment for a number of conditions that heretoforerequired surgery or lacked an adequate solution altogether. Minimallyinvasive intravascular devices especially have become popular with theintroduction of coronary stents to the U.S. market in the early 1990s.Coronary and peripheral stents have been proven to provide a superiormeans of maintaining vessel patency. In addition,they have subsequentlybeen used as filter, occluders, or in conjunction with grafts as arepair for abdominal aortic aneurysm, with fibers or other materials asocclusion devices, and as an intraluminal support for artificial valves,among other uses.

[0004] Some of the chief goals in designing stents and related devicesinclude providing sufficient radial strength to supply sufficient forceto the vessel and prevent device migration. An additional concern inperipheral use, is having a stent that is resistant to externalcompression. Self-expanding stents are superior in this regard toballoon expandable stents which are more popular for coronary use. Thechallenge is designing a device that can be delivered intraluminally tothe target, while still being capable of adequate expansion.Self-expanding stents usually require larger struts than balloonexpandable stents, thus increasing their profile. When used with fabricor other coverings that require being folded for placement into adelivery catheter, the problem is compounded.

[0005] There exists a need to have a basic stent, including a fabric orbiomaterial covering, that is capable of being delivered with a lowprofile, while still having a sufficient expansion ratio to permitimplantation in larger vessels, if desired, while being stable,self-centering, and capable of conforming to the shape of the vessel.There is a further need to have a intraluminal valve that can bedeployed in vessels to replace or augment incompetent native valves,such as in the lower extremity venous system to treat patients withvenous valve insufficiency. Such a valve should closely simulate thenormal functioning valve and be capable of permanent implantation withexcellent biocompatibility.

SUMMARY OF THE INVENTION

[0006] The foregoing problems are solved and a technical advance isachieved in an illustrative implantable valve that is deployed within abodily passage, such as a blood vessel or the heart, to regulate oraugment the normal flow of blood or other bodily fluids. The valveincludes a covering having oppositely facing curvilinear-shaped surfaces(upper and lower) against which fluid traveling in a first or seconddirection within the bodily passage exerts force to at least partiallyopen or close the valve. At least one outer edge of the coveringresiliently engages and exerts force against the wall of the vessel andhas arcuate shape that provides at least a partial seal against thewall.

[0007] In one aspect of the invention, the covering comprises aplurality of leaflets, each leaflet having a body extending from awall-engaging outer edge to a free edge which is cooperable with one ormore opposing leaflets to prevent flow in one direction, such asretrograde flow, while at least a portion of the leaflets havingsufficient flexibility, when in situ to move apart, thereby creating avalve orifice that permits flow in the opposite direction, such asnormal blood flow. The outer edge of each leaflet is adapted to engageand resilient exert force against a wall of the bodily passage such thatit extends in both a longitudinal and circumferential directions alongthe vessel wall to at least partially seal a portion of the vessellumen, while the free edge of each leaflet traverses the passagewayacross the diameter of the vessel.

[0008] In another aspect of the invention, the valve includes a framethat is covered by a piece of biocompatible material, preferably anExtracellular Collagen Matrix (ECM) such as small intestinal submucosa(SIS) or another type of submucosal-derived tissue. Other potentialbiomaterials include allographs such as harvested native valve tissue.The material is slit or otherwise provided with an opening along oneaxis to form two triangular valve leaflets over a four-sided frame. Inthe deployed configuration, the leaflets are forced open by normal bloodflow and subsequently close together in the presence of backflow to helpeliminate reflux. Other configurations include a two-leaflet valvehaving an oval or elliptically shaped frame, and valves having three ormore legs and associated leaflets, which provide a better distributionof the load exerted by the column of fluid acting on the leaflets.

[0009] In still another aspect of the invention, the frame of the deviceis modified by placing one or more of the bends under tension whichresults in the frame assuming a second shape that has superiorcharacteristics of placement within the vessel. One method of adjustingthe shape includes forming the bends in the wire at an initial angle,e.g., 150°, that is larger than the desired final angle, e.g., 90° for afour-sided valve, so when the frame is constrained into the finalconfiguration, the sides are arcuate and bow outward slightly. Thecurvature of the sides allows the sides to better conform to the roundedcountours of the vessel wall when the valve is deployed. In deviceshaving a full or partial covering of material over the frame, a secondmethod of modifying the shape is to use the material to constrain theframe in one axis. One such embodiment includes a four-sided valve withtwo triangular-shaped halves of material, such as SIS, where thematerial constrains the frame in a diamond shape. This puts the bend ofthe frame under stress or tension which permits better positioningwithin the vessel. It also allows the diagonal axis of the frame withthe slit or orifice to be adjusted to the optimal length to properlysize the frame for the vessel such that the leaflets open to allowsufficient flow, but do not open to such a degree that they contact thevessel wall. The potential benefits of both adding tension to the bendsto bow the sides and constraining the frame into a diamond shape usingthe covering, can be combined in a single embodiment or employedseparately.

[0010] In still another aspect of the present invention, the deviceincludes a frame that in one embodiment, is formed from a single pieceof wire or other material having a plurality of sides and bends eachinterconnecting adjacent sides. The bends can be coils, fillets, orother configurations to reduce stress and improve fatigue properties.The single piece of wire is preferably joined by an attachmentmechanism, such as a piece of cannula and solder, to form a closedcircumference frame. The device has a first configuration wherein thesides and bends generally lie within a single, flat plane. In anembodiment having four equal sides, the frame is folded into a secondconfiguration where opposite bends are brought in closer proximity toone another toward one end of the device, while the other opposite endsare folded in closer proximity together toward the opposite end of thedevice. In the second configuration, the device becomes a self-expandingstent. In a third configuration, the device is compressed into adelivery device, such as a catheter, such that the sides are generallybeside one another. While the preferred embodiment is four-sided, otherpolygonal shapes can be used as well. The frame can either be formedinto a generally flat configuration, or into the serpentineconfiguration for deployment. Besides rounded wire, the frame cancomprise wires of other cross-sectional shapes (e.g., oval, delta,D-shape), or flat wire. Additionally, the frame can be molded from apolymer or composite material, or formed from a bioabsorbable materialsuch as polyglycolic acid and materials with similar properties. Anothermethod is to laser cut the frame out of a metal tube, such as stainlesssteel or nitinol. Still yet another method is to spot weld together, orotherwise attach, a series of separate struts that become the sides of aclosed frame. In further alternative embodiments, the frame can be leftwith one or more open gaps that are bridged by the material stretchedover the remainder of the frame. The frame can also be formed integrallywith the covering, typically as a thickened or strengthened edge portionthat gives the device sufficient rigidity to allow it to assume thedeployed configuration in the vessel. To prevent the frame from radiallyexpanding within the vessel beyond the point which would be consideredsafe or desirable, the device can be formed into the serpentineconfiguration and a circumferentially constraining mechanism, such as atether, strut, sleeve, etc., placed around the device, or built into theframe, to expand or unfold during deployment of the device to limit itsexpansion to a given diameter, such as that which is slightly largerthan the vessel into which it is placed to allow anchoring, but notpermit the device to exert to great a force on the vessel wall.

[0011] In another aspect of the present invention, one or more barbs canbe attached to the frame for anchoring the device in the lumen of avessel. The barbs can be extensions of the single piece of wire or othermaterial comprising the frame, or they can represent a second piece ofmaterial that is separately attached to the frame by a separateattachment mechanism. An elongated barb can be used to connectadditional devices with the second and subsequent frames attached to thebarb in a similar manner. Additional barbs can be secured to the devicefrom cannulae placed over the frame. In embodiments in which the frameis formed as a single piece, such as when cut from a sheet of materialor injection molded, the barbs can be formed as integral extensions ofthe frame.

[0012] In still another aspect of the present invention, a covering,which can be a flexible synthetic material such as DACRON, or expandedpolytetrafluorethylene (ePTFE), or a natural or collagen-based material,such as an allographic tissue (such as valvular material) or axenographic implant (such as SIS), can be attached to the device withsutures or other means to partially, completely, or selectively restrictfluid flow. When the covering extends over the entire aperture of theframe, the frame formed into the second configuration functions as anvascular occlusion device that once deployed, is capable of almostimmediately occluding an artery. An artificial valve, such as that usedin the lower legs and feet to correct incompetent veins, can be made bycovering half of the frame aperture with a triangular piece of material.The artificial valve traps retrograde blood flow and seals the lumen,while normal blood flow is permitted to travel through the device. Inrelated embodiments, the device can be used to form a stent graft forrepairing damaged or diseased vessels. In a first stent graftembodiment, a pair of covered frames or stent adaptors are used tosecure a tubular graft prosthesis at either end and seal the vessel.Each stent adaptor has an opening through which the graft prosthesis isplaced and an elongated barb is attached to both frames. In anotherstent graft embodiment, one or more frames in the second configurationare used inside a sleeve to secure the device to a vessel wall.

BRIEF DESCRIPTION OF THE DRAWING

[0013]FIG. 1 depicts a top view of one exemplary embodiment of thepresent invention;

[0014]FIG. 2 depicts a pictorial view of the embodiment of FIG. 1;

[0015]FIG. 3 depicts a top view and enlarged, partial cross-sectionalviews of a second exemplary embodiment of the present invention;

[0016]FIG. 4 depicts a side view of the embodiment of FIG. 3 deployed ina vessel;

[0017]FIG. 5 depicts a enlarged partial view of the embodiment of FIG.1;

[0018]FIG. 6 depicts a partially-sectioned side view of the embodimentof FIG. 1 inside a delivery system;

[0019]FIG. 7 depicts a top view of a third embodiment of the presentinvention;

[0020]FIG. 8 depicts a side view of the embodiment of FIG. 7 deployed ina vessel;

[0021]FIGS. 9-11 depict enlarged partial views of other embodiments ofthe present invention;

[0022]FIG. 12 depicts a top view of a fourth embodiment of the presentinvention;

[0023]FIGS. 13-14 depicts side views of the embodiment of FIG. 12;

[0024]FIG. 15 depicts a top view of a fifth embodiment of the presentinvention;

[0025]FIG. 16 depicts a side view of the embodiment of FIG. 15;

[0026]FIG. 17 depicts a side view of a sixth embodiment of the presentinvention;

[0027]FIG. 18 depicts an enlarged pictorial view of a seventh embodimentof the present invention;

[0028]FIG. 19 depicts a top view of an eighth embodiment of the presentinvention;

[0029]FIG. 20 depicts a top view of a first embodiment of amulti-leaflet intraluminal valve of the present invention;

[0030]FIG. 21 depicts a top view of a second embodiment of amulti-leaflet intraluminal valve;

[0031]FIG. 21A depicts a partial top view of another embodiment ofleaflets of the present invention;

[0032]FIG. 21B depicts a top view of another embodiment of leaflet ofthe present invention;

[0033]FIGS. 22-23 depict side views of the embodiment of FIG. 21 whendeployed in a vessel;

[0034]FIGS. 24-25 depict pictorial views of the embodiments of FIG. 21when deployed in a vessel;

[0035]FIG. 26-26A depict the method of attaching the covering to theembodiment of FIG. 21;

[0036]FIG. 27 depicts a pictorial view of the basic valve of FIG. 21upon deployment with an alternative leaflet embodiment;

[0037]FIGS. 28-31 depict top views of selected embodiments of thepresent invention, made using the method shown in FIG. 28;

[0038]FIG. 32 depicts a pictorial view of an embodiment of a stent graftthat includes stent adaptors of the present invention;

[0039]FIG. 33 depicts a delivery system for deploying an embodiment ofthe present invention; and

[0040]FIG. 34 depicts a pictorial view of the present invention havingreturned to the first configuration following formation into the secondconfiguration;

[0041]FIGS. 35-36 depict top views of a three-leg valve embodiment ofthe present invention, before and after being constrained;

[0042]FIG. 37 depicts a pictorial view of the embodiment of FIG. 35 inthe deployed configuration;

[0043]FIGS. 38-39 depict top views of four-leg valve embodiments of thepresent invention, before and after being constrained;

[0044]FIG. 40 depicts a pictorial view of the embodiment of FIG. 38 inthe deployed configuration;

[0045]FIG. 41 depicts a top view of a frame formed from a sheet ofmaterial;

[0046]FIG. 41A depicts a detail view of the embodiment of FIG. 41;

[0047]FIG. 42 depicts a top view of a third embodiment of anintraluminal valve;

[0048]FIG. 43 depicts a pictorial view a frame embodiment formed into adeployed configuration;

[0049]FIG. 44 depicts a top view of an embodiment of implantable valvehaving an integrally formed frame and covering;

[0050]FIG. 45 depicts a cross-sectional view taken along line 45-45 ofFIG. 44;

[0051]FIG. 46 depicts a cross-sectional view of a second embodiment ofvalve having an integrally formed frame and covering;

[0052]FIG. 47 depicts a top view of an intraluminal valve embodimenthaving an open frame;

[0053]FIGS. 48-49 depict a pictorial views of an intraluminal valveembodiments that includes a circumferentially constraining mechanism;and

[0054]FIG. 50 depicts a top view of the embodiment of FIG. 22.

DETAILED DESCRIPTION

[0055] The invention is further illustrated by the following (preceding)pictorial embodiments, which in no way should be construed as furtherlimiting. The present invention specifically contemplates otherembodiments not illustrated but intended to be included in the appendedclaims. FIGS. 1-11, 18-19 are directed to a basic stent frame; FIGS.12-14 are directed to a single-leaflet valve; FIGS. 15-16 are directedto an occluder (or filter); FIG. 17 and 32 are directed to a stentadaptor for a stent graft, FIG. 20-27, 35-40, 42-50 are directed to amulti-leaf valve; and FIG. 28-31 are directed to a constrained framewhich can be used to form any of the other embodiments.

[0056]FIG. 1 depicts a top view of one embodiment of the medical device10 of the present invention comprising a frame 11 of resilient material,preferably metal wire made of stainless steel or a superelastic alloy(e.g., nitinol). While round wire is depicted in each of the embodimentsshown herein, other types, e.g., flat, square, triangular, D-shaped,delta-shaped, etc. may be used to form the frame. In the illustrativeembodiment, the frame comprises a closed circumference 62 of a singlepiece 59 of material that is formed into a device 10 having a pluralityof sides 13 interconnected by a series of bends 12. The depictedembodiment includes four sides 13 of approximately equal length.Alternative embodiments include forming a frame into any polygonalshape, for example a pentagon, hexagon, octagon, etc. One alternativeembodiment is shown in FIG. 19 that includes a four-sided frame 11having the general shape of a kite with two adjacent longer sides 66 andtwo adjacent shorter sides 67. In the embodiment of FIG. 1, the bends 12interconnecting the sides 13 comprise a coil 14 of approximately one anda quarter turns. The coil bend produces superior bending fatiguecharacteristics than that of a simple bend 40, as shown in FIG. 9, whenthe frame is formed from stainless steel and most other standardmaterials. The embodiment of FIG. 9 may be more appropriate, however, ifthe frame is formed from nitinol (NiTi) or other superelastic alloys, asforming certain type of bends, such as coil 14, may actually decreasefatigue life of a device of superelastic materials. Therefore, the bend12 should be of a structure that minimizes bending fatigue. Alternativebend 12 embodiments include an outward-projecting fillet 41 as shown inFIG. 10, and an inward-projecting fillet 42 comprising a series ofcurves 63, as shown in FIG. 11. Fillets are well known in the stent artas a means to reduce stresses in bends. By having the fillet extendinward as depicted in FIG. 11, there is less potential trauma to thevessel wall.

[0057] When using stainless steel wire, the size of the wire whichshould be selected depends on the size of device and the application. Anocclusion device, for example, preferably uses 0.010″ wire for a 10 mmsquare frame, while 0.014″ and 0.016″ wire would be used for 20 mm and30 mm frames, respectively. Wire that is too stiff can damage thevessel, not conform well to the vessel wall, and increase the profile ofthe device when loaded in the delivery system prior to deployment.

[0058] Returning to FIG. 1, the single piece 59 of material comprisingthe frame 11 is formed into the closed circumference 62 by securing thefirst and second ends 60,61 with an attachment mechanism 15 such as apiece of metal cannula. The ends 60,61 of the single piece 59 are theninserted into the cannula 15 and secured with solder 25, a weld,adhesive, or crimping to form the closed frame 11. The ends 60,61 of thesingle piece 59 can be joined directly without addition of a cannula 15,such as by soldering, welding, or other methods to join ends 61 and 62.Besides joining the wire, the frame could be fabricated as a singlepiece of material 59, by stamping or cutting the frame 11 from anothersheet (e.g., with a laser), fabricating from a mold, or some similarmethod of producing a unitary frame.

[0059] The device 10 depicted in FIG. 1 is shown in its firstconfiguration 35 whereby all four bends 20,21,22,23 and each of thesides 13 generally lie within a single flat plane. To resilientlyreshape the device 10 into a second configuration 36, shown in FIG. 2,the frame 11 of FIG. 1 is folded twice, first along one diagonal axis 94with opposite bends 20 and 21 being brought into closer proximity,followed by opposite bends 22 and 23 being folded together and broughtinto closer proximity in the opposite direction. The secondconfiguration 36, depicted in FIG. 2, has two opposite bends 20,21oriented at the first end 68 of the device 10, while the other oppositebends 22,23 are oriented at the second end 69 of the device 10 androtated approximately 90° with respect to bends 20 and 21 when viewed incross-section. The medical device in the second configuration 36 can beused as a stent 44 to maintain an open lumen 34 in a vessel 33, such asa vein, artery, or duct. The bending stresses introduced to the frame 11by the first and second folds required to form the device 10 into thesecond configuration 36, apply force radially outward against the vesselwall 70 to hold the device 10 in place and prevent vessel closure.Absent any significant plastic deformation occurring during folding anddeployment, the device in the second configuration 36 when not with thevessel or other constraining means, will at least partially return tothe first configuration 25, although some deformation can occur asdepicted in FIG. 34, depending on the material used. It is possible toplastically form the stent into this configuration which represents anintermediate condition between the first configuration (which it alsocan obtain) and the second configuration. It is also possible toplastically deform the device 10 into the second configuration 36, suchthat it does not unfold when restraint is removed. This might beparticularly desired if the device is made from nitinol or asuperelastic alloy.

[0060] The standard method of deploying the medical device 10 in avessel 33, depicted in FIG. 6, involves resiliently forming the frame 11into a third configuration 37 to load into a delivery device 26, such asa catheter. In the third configuration 37 the adjacent sides 13 aregenerally beside each other in close proximity extending generally alongthe same axis. To advance and deploy the device from the distal end 28of the delivery catheter 26, a pusher 27 is placed into the catheterlumen 29. When the device 10 is fully deployed, it assumes the secondconfiguration 36 within the vessel as depicted in FIG. 2. The sides 13of the frame, being made of resilient material, conform to the shape ofthe vessel wall 70 such that when viewed on end, the device 10 has acircular appearance when deployed in a round vessel. As a result, sides13 are arcuate or slightly bowed out to better conform to the vesselwall.

[0061] A second embodiment of the present invention is depicted in FIG.3 wherein one or more barbs 16 are included to anchor the device 10following deployment. As understood, a barb can be a wire, hook, or anystructure attached to the frame and so configured as to be able toanchor the device 10 within a lumen. The illustrative embodimentincludes a first barb 16 with up to three other barbs 17,71,72,indicated in dashed lines, representing alternative embodiments. Asdepicted in detail view A of FIG. 3, the barb combination 38thatcomprises barbs 17 and 18, each barb is an extension of the single piece59 of material of the frame 11 beyond the closed circumference 59. Theattachment cannula 15 secures and closes the single piece 59 of materialinto the frame 11 as previously described, while the first and secondends 60,61 thereof, extend from the cannula 15, running generallyparallel with the side 13 of the frame 11 from which they extend, eachpreferably terminating around or slightly beyond respective bends 20,23.To facilitate anchoring, the distal end 19 of the barb 16 in theillustrative embodiment contains a bend or hook.

[0062] Optionally, the tip of the distal end 19 can be ground to asharpened point for better tissue penetration. To add a third and fourthbarb as shown, a double ended barb 39 comprising barbs 71 and 72 isattached to the opposite side 13 as defined by bends 21 and 22. Unlikebarb combination 38, the double barb 39, as shown in detail view B ofFIG. 3, comprises a piece of wire, usually the length of barbcombination 38, that is separate from the single piece 59 comprising themain frame 11. It is secured to the frame by attachment mechanism 15using the methods described for FIG. 1. FIG. 4 depicts barb 17 (and 18)engaging the vessel wall 70 while the device 10 is in the second,deployed configuration 36. While this embodiment describes up to a fourbarb system, more than four can be used.

[0063]FIG. 7 depicts a top view of a third embodiment of the presentinvention in the first configuration 35 that includes a plurality offrames 11 attached in series. In the illustrative embodiment, a firstframe 30 and second frame 31 are attached by a barb 16 that is securedto each frame by their respective attachment mechanisms 15. The barb 16can be a double-ended barb 39 as shown in FIG. 3 (and detail view B)that is separate from the single pieces 59 comprising frames 30 and 31,or the barb may represent a long extended end of the one of the singlepieces 59 as shown in detail view A of FIG. 3. Further frames, such asthird frame 32 shown in dashed lines, can be added by merely extendingthe length of the barb 16. FIG. 8 depicts a side view of the embodimentof FIG. 7 in the second configuration 36 as deployed in a vessel 33.

[0064]FIGS. 12-18 depict embodiments of the present invention in which acovering 45 comprising a sheet of fabric, collagen (such as smallintestinal submucosa), or other flexible material is attached to theframe 11 by means of sutures 50, adhesive, heat sealing, “weaving”together, crosslinking, or other known means. FIG. 12 depicts a top viewof a fourth embodiment of the present invention while in the firstconfiguration 35, in which the covering 45 is a partial covering 58,triangular in shape, that extends over approximately half of theaperture 56 of the frame 11. When formed into the second configuration36 as shown in FIGS. 13-14, the device 10 can act as an artificial valve43 such as the type used to correct valvular incompetence. FIG. 13depicts the valve 43 in the open configuration 48. In this state, thepartial covering 58 has been displaced toward the vessel wall 70 due topositive fluid pressure or flow in a first direction 46, e.g., normalvenous blood flow, thereby opening a passageway 65 through the frame 11and the lumen 34 of the vessel 33. As the muscles relax, producing flowin a second, opposite direction 47, e.g., retrograde blood flow 47, asshown in FIG. 14, the partial covering 58 acts as a normal valve bycatching the backward flowing blood and closing the lumen 34 of thevessel. In the case of the artificial valve 43, the partial covering 58is forced against the vessel wall to seal off the passageway 65, unlikea normal venous valve which has two leaflets, which are forced togetherduring retrograde flow. Both the artificial valve 43 of the illustrativeembodiment and the normal venous valve, have a curved structure or cuspthat facilitates the capture of the blood and subsequent closure. Inaddition to the triangular covering, other possible configurations ofthe partial covering 58 that result in the cupping or trapping of fluidin one direction can be used. Selecting the correct size of valve forthe vessel ensures that the partial covering 58 properly seals againstthe vessel wall 70. If the lumen 34 of the vessel is too large for thedevice 10, there will be retrograde leakage around the partial covering58.

[0065]FIG. 15 depicts a top view of a fifth embodiment of the presentinvention in the first configuration 35, whereby there is a fullcovering 57 that generally covers the entire aperture 56 of the frame11. When the device 10 is formed into the second configuration 36, asdepicted in FIG. 16, it becomes useful as an occlusion device 51 toocclude a duct or vessel, close a shunt, repair a defect, or otherapplication where complete or substantially complete prevention of flowis desired. As an intravascular device, studies in swine have shownocclusion to occur almost immediately when deployed in an artery or theaorta with autopsy specimens showing that thrombus and fibrin which hadfilled the space around the device. The design of the present inventionpermits it to be used successfully in large vessels such as the aorta.Generally, the occlusion device should have side 13 lengths that are atleast around 50% or larger than the vessel diameter in which they are tobe implanted.

[0066]FIGS. 17-18 depict two embodiments of the present invention inwhich the device 10 functions as a stent graft 75 to repair a damaged ordiseased vessel, such as due to formation of an aneurysm. FIG. 17 showsa stent graft 75 having a tubular graft prosthesis 54 that is held inplace by a pair of frames 11 that function as stent adaptors 52,53. Eachstent adaptor 52,53 has a covering attached to each of the frame sides13 which includes a central opening 55 through which the graftprosthesis 54 is placed and held in place by friction or attachment toprevent migration. One method of preventing migration is placement of astent adaptor 52,53 according to the present invention at each end andsuturing the graft prosthesis 54 to the covering of the stent adaptors52,53. The stent adaptors 52,53 provide a means to seal blood flow whilecentering the graft prosthesis in the vessel. A long double-ended barb39 connects to each stent adaptor 52,53 and assists to further anchorthe stent graft 75. In the embodiment depicted in FIG. 18, the covering45 comprises a outer sleeve 64 that is held in place by first and second30,31 frames that function as stents 44 to hold and seal the sleeve 64against a vessel wall and maintain an open passageway 65. In theillustrative embodiment, the stents 44 are secured to the graft sleeve64 by sutures 50 that are optionally anchored to the coils 14 of thebends 12. If the embodiment of FIG. 18 is used in smaller vessels, asingle frame 11 can be used at each end of the stent graft 75. Anotherstent graft 75 embodiment is depicted in FIG. 32 for repairing a vesseldefect 97, such as an aneurysm in a bifurcated vessel. The stent adaptor52 of the present invention is placed in the common vessel 96 such asthe abdominal aorta. Two tubular grafts 54 are secured within anaperture 55 in the covering 45 of the frame 11 by one or more internalstent adapters 102, or another type of self-expanding stent, that biasthe opening of the grafts 54 against the surrounding covering 45 toprovide an adequate seal. Each leg 98,99 of the stent graft prosthesis75 transverses the vessel defect 97 and feeds into their respectivevessel branches 100,101 such the right and left common iliac arteries.As with the embodiment of FIG. 17, a second stent adapter 53 can be usedto anchor the other end of the tubular graft 54 in each vessel branch100,101.

[0067]FIGS. 20-27 and 35-41 depict embodiments of present inventions inwhich the device 10 comprises an implantable valve having multipleleaflets 25 that act together to regulate and augment the flow of fluidthrough a duct or vessel 33, or within the heart to treat patients withdamaged or diseased heart valves. The covering 45 of each of theseembodiments includes one or a series of partial coverings 58 that formthe leaflets 25 of the valve. As with the other embodiments, thecovering 45 may comprise a biomaterial or a synthetic material. WhileDACRON, expanded polytetrafluoroethylene (ePTFE), or other syntheticbiocompatible materials can be used to fabricate the covering 45, anaturally occurring biomaterial, such as collagen, is highly desirable,particularly a specially derived collagen material known as anextracellular matrix (ECM), such as small intestinal submucosa (SIS).Besides SIS, examples of ECM's include pericardium, stomach submucosa,liver basement membrane, urinary bladder submucosa, tissue mucosa, anddura mater. SIS is particularly useful, and can be made in the fashiondescribed in Badylak et al., U.S. Pat. No. 4,902,508; IntestinalCollagen Layer described in U.S. Pat. No. 5,733,337 to Carr and in 17Nature Biotechnology 1083 (November 1999); Cook et al., WIPO PublicationWO 98/22158, dated 28 May 1998, which is the published application ofPCT/US97/14855. Irrespective of the origin of the valve material(synthetic versus naturally occurring), the valve material can be madethicker by making multilaminate constructs, for example SIS constructsas described in U.S. Pat. Nos. 5,968,096; 5,955,110; 5,885,619; and5,711,969. Animal data show that the SIS used in venous valves of thepresent invention can be replaced by native tissue in as little as amonth's time. In addition to xenogenic biomaterials, such as SIS,autologous tissue can be harvested as well, for use in forming theleaflets of the valve. Additionally Elastin or Elastin Like Polypetides(ELPs) and the like offer potential as a material to fabricate thecovering or frame to form a device with exceptional biocompatibility.Another alternative would be to used allographs such as harvested nativevalve tissue. Such tissue is commercially available in a cryopreservedstate.

[0068] To more completely discuss and understand the multi-leaflet valve43 embodiments of FIGS. 20-27,35-41, it is useful to now add certainsupplemental terminology which in some instances, could be applied tothe embodiments depicted in the earlier figures. In the illustrativemulti-leaflet embodiments, the valve 43 is divided into a plurality oflegs 113, each of which further comprises a leaflet 25. To anchor,support, and provide the proper orientation of the leaflets 25, aseparate or integral frame 11 is included, such as the wire frame 11depicted in FIG. 1. Ideally, the wire used to construct the frame ismade of a resilient material such as 302,304 stainless steel; however, awide variety of other metals, polymers, or other materials are possible.It is possible for the frame to be made of the same material as theleaflets 25. One other example of a suitable frame material would be asuperelastic alloy such as nitinol (NiTi). Resiliency of the frame 11,which provides radial expandability to the valve 43 when in the secondconfiguration 36 for deployment, is not necessarily an essentialproperty of the frame. For example, optional barbs 16 can provide themeans to anchor the valve 43 after delivery, even if the valve 43 lackssufficient expansile force to anchor itself against the vessel wall.Additionally, the frame can comprise a ductile material with the device10 being designed to be balloon expandable within the vessel.

[0069] Typically, when used as a valve to correct venous insufficiencyin the lower extremities, the valve 43 in situ comprises a plurality ofbends 12 of the frame, that provide the majority of the outward radialforce that helps anchor the device to vessel wall 70, as depicted inFIGS. 22-27. When deployed, the frame assumes the undulating orserpentine configuration characteristic of the invention with a firstseries of bends 115 of the first or proximal end alternating with asecond series of bends 116 of the second or distal end, with the secondor distal bends 116 being located at the bottom of the valve distal tothe heart and the first or proximal bends 115 being located at the topof the valve proximal to the heart. It should be understood that thevalve can assume other orientations, depending on the particularclinical use, and thus, any directional labels used herein (‘distal’,‘top’, etc.) are merely for reference purposes. The leaflet 25, whichgenerally covers the valve leg 113 and therefore, assumes the sameroughly triangular ‘U’ or ‘V’ shape of that portion of the frame 11perimeter, includes an resilient arcuate outer edge 112 that conforms toand/or seals with the contours of the vessel wall 70, and an inner edge111 that traverses the vessel lumen 34. The central portion or body 156of the leaflet 25 extends inward from the vessel wall 70 and outer edge112 in an oblique direction toward the first end 68 of the valve 43where it terminates at the inner edge 111 thereof. The valve leafletsthat come in contact with the vessel wall can also be arcuate as thesupporting frame to better conform to and seal wit the vessel wall. Theleaflets 25 assume a curvilinear shape when in the deployedconfiguration 36. The portion of the body 156 proximate the inner edge111 is sufficiently flexible such that is can move in and out of contactwith the inner edge 111 the opposite or other leaflets 25; however, theremainder of the body 156, particular that near the outer edge 112 orsecond end 69 of the device 10, can be made less flexible or even rigidin some instances, essentially functioning more for support, similar tothe function of the frame 11, rather than to cooperate with otherleaflet(s) 25. FIGS. 20-27 depict the present invention as animplantable, intraluminal, vascular adapted for use as a implantablemulti- leaflet valve 43 including a stent 44 or frame 11 with at least apartial covering 58. The covering comprises a first and a second valveleaflets 78,79 that at least partially seal the aperture 56 within theframe 11 while the valve 43 is in the deployed configuration 36 andforms the opening 117 or valve orifice which regulates the flow of fluid46,47 through the valve. FIG. 20 shows the device 10 in the first,generally planar configuration 35 where the frame 11 is generallyrectangular or in particular square in shape. The partial covering 58forming the leaflets 78,79 generally extends across the entire frame 11with the aperture 56 comprising a slit 108 that extends across the firstaxis 94 of the frame 11, the first axis being defined as traversingdiagonally opposite bends (22 and 23 in this example) that are in linewith the valve orifice 117 that forms the valve 43. The covering 45 istherefore divided into at least first and second portions (making it apartial covering 58) which define the first and second valve leaflets78,79. To form the leaflets 78,79, a complete covering 45 can be slitopen along the axis after it is affixed to the frame, or at least firstand secon dadjacent triangular portions (partial coverings 58) can beseparately attached, eliminating the need for mechanically forming aslit 108. In the embodiment of FIG. 20, the slit 108 is made in thecovering 45 such that the slit terminates a few millimeters from each ofthe corner bends 22,23, creating a pair of corner gaps 155, therebyeliminating two of the most likely sources of leakage around the valve43. In the illustrative embodiments, the outer edge 112 of the partialcovering 58 that comprises the leaflet 25 is stretched over the frame 11comprising the valve leg 113 and sutured or otherwise attached asdisclosed herein. The leaflet 25 is secured in place such that thematerial is fairly taut, such that when the valve 43 is situated in thevessel 33 and its diameter constrained to slightly less than the valvewidth 146, the leaflet 25 assumes a relatively loose configuration thatgives it the ability to flex and invert its shape, depending on thedirection of fluid flow. The inner edge 111 of the leaflet 25 isgenerally free and unattached to the frame and generally extends betweenthe bends 22 and 23 (the bends 115 of the first end) of the valve leg113. The inner edge 111 may be reinforced by some means, such asadditional material or thin wire, that still would allow it to besufficiently pliable to be able to seal against another leaflet 25 whenretrograde flow 47 forces the leaflets 78,79 together. The leaflet 25 issized and shaped such that the inner edge 111 of one leaflet 78 can meetor overlap with the inner edge 111 of the opposing leaflet 79 (orleaflets, e.g., 119,120), except when degree of normal, positive flow 46is sufficient to force the leaflets 25 open to permit fluid passagetherethrough.

[0070] The embodiments of FIGS. 21-27 are configured into an elongateddiamond shape 153 in the planar configuration 35 with the distancebetween the two bends 22,23 aligned with the valve orifice 117 and firstaxis 94 being less than the distance between bends 20 and 21 along thesecond, perpendicular axis 95. This diamond configuration 153 can beaccomplished by forming the frame 11 into that particular shape, orconstraining a square frame into a diamond shape 153, which will bediscussed later. By configuring the valve 43 into the diamond shape 153,the valve legs 127,128 become more elongated in shape, which can helpadd stability when positioning the device 10 during deployment, providesmore surface area to receive retrograde flow, and more closely mimics anatural venous valve. In the deployed configuration 36 of the embodimentof FIG. 21, which is shown in FIGS. 22-25, the valve leaflets 78,79 areforced apart by the normal pulsatile blood flow 46 (FIGS. 22,24). Therespective valve leaflets 78,79 naturally move back into closerproximity following the pulse of blood. Retrograde blood flow 47 forcesthe valve leaflets 78,79 against one another, as depicted in FIGS. 23and 25 thereby closing off the lumen 34 of the vessel 33 and the valveorifice 117.

[0071]FIGS. 21A-21B depict embodiments of the valve 43 in which eachleaflet 78,79 includes a flap 77 of overhanging material along the slitedge 111 to provide advantageous sealing dynamics when the valve 43 isin the deployed configuration 36 as depicted in FIGS. 22-25. The flaps77 are typically formed by suturing two separate pieces of covering 45material to the frame such that the inner edge 111 is extendable overthe slit 108 and inner edge 111 of the adjacent leaflet 25. Byoverlapping with an adjacent flap 77 or leaflet 25, the flap 77 canprovide additional means to help seal the valve orifice 117. Twoembodiments of leaflets 25 with flaps 77 are shown. In FIG. 21A, theinner edge 111 is basically straight and extends over the first axis 94of the frame 11. The flaps 77 can be cut to create a corner gap 155 thatcovers and seals the corner region around the bend 22,23. In theembodiment of FIG. 21B, the flap 77 is cut such that there is a notch157 in the leaflet where the leaflet meets the corner bends 22,23. Whilethese flaps 77 may provide benefit in certain embodiments, the optionalflaps 77 shown in FIG. 21 are not necessary to provide a good sealagainst backflow 47 if the valve 43 and leaflets 25 are properly sizedand configured.

[0072]FIGS. 26-26A depict one method of affixing a covering 45comprising a biomaterial, such as SIS, to the frame 11 which has beenconstrained using a temporary constraining mechansim 121, such as asuture, to acheive the desired frame configuration. As shown in FIG. 26,the covering 45 is cut larger than the frame 11 such that there is anoverhang 80 of material therearound, e.g, 5-10 mm. The frame 11 iscentered over the covering 45 and the overhang 80 is then folded overfrom one long side 142, with the other long side 143 subsequently beingfolded over the first. As shown in FIG. 26A, the covering 45 is suturedto the frame along one side 142, typically using forceps 158 and needle,thereby enclosing the frame 11 and the coiled eyelet 14 with theoverhang 80 along side 142. The covering 45 is sutured to the frame withresorbable or non-resorbable sutures 50 or some other suitable method ofattaching two layers of biomaterials can be used. In the case of SIS, asingle ply sheet, usually about 0.1 mm thick, is used in the hydratedcondition. In the illustrative embodiments, 7-0 Prolene suture is used,forming a knot at one bend (e.g., bend 20), then continuing to the nextbend (e.g., 22) with a running suture 50, penetrating the layers of SISaround the frame at about 1-2 mm intervals with loops formed to hold thesuture 50 in place. When the next coil turn 14 is reached, several knotsare formed therethrough, and the running suture 50 continues to the nextcoil turn 14. If barbs are present, such as shown in the embodiment ofFIG. 21, the suture 50 is kept inside of the barbs 16 located about eachcoil turn 14. In the illustrative example, the covering 45 is affixed tothe frame 11 such that one side of the overhang 80 is not sutured overthe other side in order to maintain the free edge of the overhang 80,although the alternative condition would be an acceptable embodiment.Alternative attachment methods include, but are not limited to, use of abiological adhesive, a cross-linking agent, heat welding, crimping, andpressure welding. For synthetic coverings, other similar methods ofjoining or attaching materials are available which are known in themedical arts. The covering 45, whether made from a biomaterial orsynthetic material, can be altered in ways that improve its function,for example, by applying a coating of pharmacologically active materialssuch as heparin or cytokines, providing a thin external cellular layer,e.g., endothelial cells, or adding a hydrophilic material or othertreatment to change the surface properties.

[0073] Once the covering 45 has been sutured into place or otherwiseattached to the frame, the overhang 80 is folded back away from theframe, as shown on the second side 143 of the frame of FIG. 26A, andpart of the excess overhang 80 is trimmed away with a scalpel 159 orother cutting instrument to leave a 2-4 mm skirt around the frame 11.The overhang 80 or skirt provides a free edge of SIS (or material withsimilar remodeling properties) to help encourage more rapid cellingrowth from the vessel wall, such that the SIS replaces native tissueas quickly as possible. An unattached edge of the overhang 80 can alsoform a corner flap 81 or pocket as depicted in FIG. 27. This corner flap81 can serve to catch retrograde blood flow 47 to provide a better sealbetween the device 10 and the vessel wall 70 as well as providing animproved substrate for ingrowth of native intimal tissue from the vessel33, if made of SIS or another material with remodeling properties.

[0074] Referring now to FIGS. 28-31, the frame 11 used to form the valve43 embodiments, e.g., FIGS. 20-27, that are placed in the legs or otherdeep veins as replacement for incompetent venous valves, is sizedaccording to the size of the target vessel. For example, a typicalvenous valve might be made of 0.0075″ 304 stainless steel mandril wirewith an attachment mechanism 15 comprising 23 to 24 gauge thin-wallstainless steel cannula or other tubing. Larger wire (e.g., 0.01″) andattachment cannula 15 are typically used for valves 43 of the largerdiameter (greater than 15 mm). Selection of the attachment cannula 15depends on competing factors. For example, use of larger gaugeattachment cannula 15 results in a slightly increased device 10 profile,yet it includes additional room for flux when the attachment mechanism15 is soldered over the continuous wire 59 comprising the frame 11. FIG.30 best depicts an uncovered frame 11 used to form a venous valve 43,wherein the length of the sides 13 typically range from about 15 to 25mm. For larger frames, heavier gauge wire is typically used. Forexample, 25 mm frames might use 0.01″ wire, with larger diameterembodiments such as stent occluders used for femoral bypass or stentadaptors, such as shown in FIGS. 17 and 32, requiring an even heaviergauge. The appropriate gauge or thickness of the frame wire also dependson the type of alloy or material used. As previously disclosed, theframe is typically formed in a generally flat configuration and thenmanipulated into its characteristic serpentine configuration and loadedinto a delivery system. Therefore, the frame usually will tend toreassume the first or generally flat configuration if the restraint ofthe delivery system or vessel is removed. Deformation of the frame 11can occur after it has been manipulated into the second configuration,however, such that it no longer will lie completely flat, as depicted inFIG. 34. This angle of deformation 129, which varies depending on theframe thickness and material used, generally does not compromise thefunction of the device 10, which can be reconfigured into the serpentineconfiguration (of the second, deployed configurations) without loss offunction.

[0075] The frame 11 of the present invention can be made either byforming a series of bends in a length of straight wire and attaching thewire to itself, as previously discussed, to form a closed configuration,or the frame 11 can be formed in the deployment (second) configuration35 as depicted in FIGS. 41-41A by cutting it out of a flat sheet 152 ofmaterial, e.g., stainless steel or nitinol. Further finishing procedurescan then be performed after it has been cut or formed, such aspolishing, eliminating sharp edges, adding surface treatments orcoatings, etc. In addition to metal, the frame 11 can comprise one ormore polymers, composite materials, or other non-metallic materials suchas collagen with the frame either being cut from a thin sheet of thematerial, or molded into the deployment configuration 36 as depicted inFIG. 43. Unlike the majority of the depicted embodiments, the frame 11of FIG. 43 does not naturally assume a flattened configuration 35 whenthe device 10 is unconstrained by the vessel or delivery system.

[0076] The illustrative embodiments of FIGS. 41-41A and 43 includeintegral barbs 124 that extend from the frame 11, which being formed asa closed frame, does not have free ends 60,61 that can be used to serveas barbs 16 as depicted in FIG. 3 and other embodiments. FIGS. 41-41Adepict a series of integral barbs 124 comprising V-shaped cuts 139transversing the thickness of the flat metal frame 11, which are bentoutward to form the barb 16. In the embodiment of FIG. 43, the integralbarbs 124 are formed along with the frame 11 with two extending from theframe at either side of each bend 12. These integral barbs 124 can bedesigned into the mold if the frame 11 is formed out of a polymermaterial. The number, arrangement, and configuration of the integralbarbs 124 is generally not critical and can vary according to designpreference and the clinical use of the device. The barbs 16 may or maynot penetrate the covering, depending on their design and other factors,including the thickness and type of covering used.

[0077] While the frame embodiment of FIG. 43 can be formed from avariety of medical grade polymers having properties that permit theframe to function as a supporting structure for the valve leaflets78,79, it should be noted that for some uses, it may be desirable toform the frame 11 from a material that can be degraded and adsorbed bythe body over time to advantageously eliminate a frame structure canwould remain in the vessel as a foreign body and that could possiblyfracture and/or cause perforation of the vessel wall. A number ofbioabsorbable homopolymers, copolymers, or blends of bioabsorbablepolymers are known in the medical arts. These include, but are notnecessarily limited to, poly-alpha hydroxy acids such as polyactic acid,polylactide, polyglycolic acid, or polyglycolide; trimethlyenecarbonate; polycaprolactone; poly-beta hydroxy acids such aspolyhydroxybutyrate or polyhydroxyvalerate; or other polymers such aspolyphosphazines, polyorganophosphazines, polyanhydrides,polyesteramides, polyorthoesters, polyethylene oxide, polyester-ethers(e.g., polydioxanone) or polyamino acids (e.g., poly-L-glutamic acid orpoly-L-lysine). There are also a number of naturally derivedbioabsorbable polymers that may be suitable, including modifiedpolysaccharides such as cellulose, chitin, and dextran or modifiedproteins such as fibrin and casein.

[0078]FIGS. 44-46 depicts two exemplary embodiments in which the frame11 is integral with the covering 45. In the embodiment of FIG. 44, thevalve 43 is formed as a single piece of material, such as a flexiblepolymeric or collagen-based material, whereby there is a thin, compliantcentral portion comprising the covering 45 or leaflets 78,79, and athickened edge 141 portion that comprises the frame 11. The valve 43,shown in the generally flat configuration 35, can be also formed intothe deployment configuration 36 (see FIG. 43). Optionally, the materialof the frame 11 portion can be subjected to treatments or processes thatadd rigidity or other desired characteristics that permit the frame tobetter support the covering 45 portion or anchor the device 10 to thevessel wall. As with the embodiment of FIG. 43, optional intergral barbs124 can be included along the frame 11. In addition to forming athickened edge 141 to serve as the frame 11, other layers of differentmaterials can be laminated to or blended with the edge portion toprovide the desired properties. As another alternative to the thickenededge 141 portion of FIGS. 44-45, the outside edge 112 of the covering 45can be folded over itself to form a rolled edge 140 (FIG. 46) that addsrigidity to serve as a frame 11. The rolled edge 140 can be held inplaced with a glue, resin, or similar bonding agent 144. For example,the covering 45 and rolled edge 140 can comprise a sheet of SIS with abonding agent 144 such as collagen glue or other bioabsorbable materialused to secure the rolled portion and after hardening, to add thenecessary degree of rigidity for the valve 43 (or occluder, filter,stent adaptor, etc.) to assume the deployment configuration within thevessel. Excess of the bonding agent 144 can be fashioned to structuralelements that can serve to help anchor the device 10 within the vessel.It is also within the scope of the invention to eliminate a discernableframe 11 by changing the material or material properties along the outeredge 112 of the leaflets, by adding or incorporating one or moredifferent material or agents along the outer edge 112 of covering 45such that the stiffness and/or resiliency increased, thereby allowingthe frame to hold a desired shape during deployment, while stillallowing the adjacent covering material to be sufficiently flexible tofunction as a leaflet 25. If the illustrative valve 43 lacks the radialexpandability to anchor itself to the vessel wall, it may be mounted ona balloon to expand the valve 43 and anchor the barbs, if present, intothe vessel wall.

[0079] The illustrative embodiments of the present invention generallyinclude a closed frame 11 to give the device 10 its form. FIG. 47depicts an example in which the frame 11 portion is not a closedstructure. Rather, a portion of the covering 45 used to span a gap 145in the frame such that a portion of the outside edge 112 (of leaflet 79in this example) is unsupported therealong. The length of the gaps 145and their distribution can vary as long as the frame 11 is still able tofulfill its role to support and define the shape of the valve 43 ordevice 10.

[0080]FIGS. 21-31 depict various embodiments in which the bends20,21,22,23 are placed in a resiliently tensioned or stressed stateafter being initially formed such that the bends were not under tension.The term ‘tension’, as used herein, is meant to describe generally aforced applied to a resilient material or structure against the naturaltendency of the material or structure, whether or not the force is infact tensile, compression, or torsional. Further incremental forcesapplied will generally encounter greater resistance than would otherwisebe exhibited by the material or structure, such as a compression spring,which exerts a force (resilience) resisting compression proportional tothe distance the spring has already been compressed. The addition oftension to one or more bends 12 of the device frame 11 can alter theproperties of the frame 11 and result in improved sealingcharacteristics or the ability of the device 10 to impinge upon thevessel wall 70 to prevent migration or shifting. In the illustrativeembodiments, the coil turn 14 is formed as previously disclosed wherebyeach bend 12 is in a untensioned state with the adjacent sides 13 havingan initial angle after formation of the bend 12. For example, in theembodiment of FIG. 20, the initial angle 109 after the bends are formedand the final angle 110 after the frame 11 is assembled are bothapproximately 90°. Therefore, the bends 12 of the embodiment of FIG. 20are not placed under any significant degree of tension. In theembodiments of FIGS. 21-31, the frame is restrained to permanently placethe bends 12 under tension such that the angle between the sides 122,123adjacent to the bend 12 is increased or decreased by some method ofmanipulation to produce a resiliently tensioned bend 118 (FIGS. 26 and29) having a final angle 110 different than the initial angle 109 (e.g.,FIG. 28).

[0081] Referring particularly to FIGS. 21-28, the covering 45 (includinga full or a partial covering 58) can be attached to the frame 11 of thevalve 43 or other embodiment of the present invention, to constrain agenerally untensioned square frame 11 (such as in FIG. 1) andsubsequently form an altered shape 82, such as a diamond 153, in whichthe distance between bends 20 and 21 is lengthened and the distancebetween bends 22 and 23 is shortened. By way of example, and using FIG.21 as reference, the angle 110 measured between the adjacent sides 13from bends 20 and 21 might decrease to 70-80° with a increase in thecorresponding angles 161 measured at bends 22 and 23 to 100-110°. Thismanipulation of the frame 11 shape serves to add tension in each of thebends, which allows better positioning of the device 10 against thevessel wall 70 while in the deployed configuration, as shown in FIGS.22-25. Additionally, constraining the frame 11 along the first axis 94of the slit 108 allows that distance 146 to be adjusted to provide theoptimum size for the vessel 33 into which the valve 43 is to beimplanted. Assuming a resilient frame 11 is being used that makes thevalve 43 radially expandable, it would normally be preferential toslightly oversize the valve 43 along at the width 146 of the frame 11(along first axis 94) when the valve 43 is in the generally flattenedconfiguration 35, thereby causing the leaflets 78,79 to relax slightlywhen the valve 43 is in the deployed configuration 36 and beingconstrained slightly by the vessel 33. The proper length of theconstrained frame 11 as measured diagonally between bends 22 and 23 iscalculated such that the leaflets 78,79 open by an effective amount inthe presence of blood flow 46 that most closely mimics that found in anormal functioning valve.

[0082] Dog studies by Karino and Motomiya (Thrombosis Research36:245-257) have demonstrated that there is about a 60 to 70%constriction of blood flow through the natural valve. In the valve 43 ofthe present invention, the leaflets 25 should ideally span about 30-60%of the vessel 33 diameter across. If it is much less than 30%, bloodflow 46 may be impeded to an unacceptable degree, while if the leaflets78,79 are allowed to fully open, they can adhere to the vessel wall 70and therefore, not close properly in the presence of retrograde flow 47.The frame 11 can be formed or constrained such that the distance 146between points 22,23 lies between πr, which would allow the valve toopen to the full extent that the vessel allows, and 2r in which thevalve 43 is stretched tight across the frame 11 and is very limited inthe amount of blood that will allow to pass through. To give theleaflets the flexibility and compliance to open to permit flow and thenclose to seal against backflow, the slit axis distance 146 of the valve43 should be oversized with respect to the diameter of the vessel intowhich it is to be placed. Constraining the valve 43 along the first axis94 such that it sized a few mm larger than the lower extreme (2r) or afew mm larger than the upper extreme (πr), not only allows the leafletsto function in a more optimal manner, but also allows the valve 43 tosafely and effectively impinge on the vessel wall to seal and reduce thepossibility of migration. The ideal amount of oversize is largelydependent on the size and diameter of the frame 11 prior to resizing.FIG. 49 depicts a schematic top view of the valve of FIG. 22 showing thelength 147 of the orifice, the width 148 of the orifice, the portion 154of the vessel occluded by a leaflet 25, and the corner gaps 155 thanexist between each lateral edge 156 of the valve orifice 117 and theouter edge 112 of the leaflet 25 (or the frame 11). The followingformula can be to approximate the elliptic circumference (C) of thevalve orifice 117, where a=one half the length 147 of the orifice, andb=one half the width 148 of the orifice 117:$C = {2{\pi \left\lbrack \frac{\left( {a^{2} + b^{2}} \right)}{2} \right\rbrack}^{\frac{1}{2}}}$

[0083] Assuming that we wish to size the valve 43 to produce an orifice117 that opens approximately 30-60% of the vessel lumen 34 (with theoccluded portions 154 comprising 40-70% of the same), the precedingformula can be used to determine the amount of oversize that producesthe desired characteristics. The amount of oversize (valve width 146 inthe flat configuration minus the diameter of the vessel lumen 34) wouldgenerally range from 1-2 mm for smaller valves (those placed in 8-9 mmvessels) up to 3-4 mm for valves intended for larger vessels (17-21 mm). For example, a valve intended for a 14 mm vessel should ideally havea 2-3 mm oversize if the range of 30-60% opening is to be maintained. Ifthe frame 11 of a valve 43 having 20 mm sides is constrained such thatthe distance between bends 22 and 23 is adjusted to approximately 16 mm, the valve 43 opens approximately 43%, which is well within the mostdesired range. If constrained to 17 mm , the valve 43 is able to open upto approximately 55% of the vessel diameter. In contrast, oversizing thevalve 43 by 6 mm, produces a large orifice 117 of 83% which lies outsidethe target range, although it would certainly produce a valve 43 capableof opening and closing in response to fluid flow 46,47. To produce avalve 43 in which the valve width in the generally flattenedconfiguration 35 is 17-18 mm , which would be a valve 43 sized toaccommodate a 14-15 mm vessel, the 20 mm frame 11 should be constrainedsuch that the distance between bends 22 and 23 is 15 mm prior toaddition of the covering 45, if a compliant material such as SIS isused. As depicted in FIG. 26, the frame 11 is constrained across thefirst axis 94 using a temporary constraining mechanism 121, such as bytying a suture through the coil turns 14 of bends 22 and 23 to pull themtoward one another until a distance of 15 mm is reached. After thecovering 45 has been attached, such as by the method previouslydisclosed, the temporary constraining suture 121 is cut, which resultsin a slight expansion in the width of the frame 11 as the SIS stretchesunder the tension of the constrained frame, resulting in the desiredfinal width of 17-18 mm. The amount of expansion varies with thecompliance of the particular covering 45 as well as the resiliency ofthe frame 11. Although the desired final width 146 of the constrainedframe 11 can result from a relatively wide range of initial frame 11sizes, depending on how much the frame is constrained, generally, largersized frames (e.g., sides measuring about 25 mm ) are most suitable forlarger vessels (e.g., 16-21 mm in diameter), while smaller frames (e.g.,15 mm ) are most suitable for smaller diameter vessels (e.g., 8-9 mm).While this range represents the most common sizes used for correctingvenous valve insufficiency in the lower legs, valves 43 of the presentinvention can be made in a much larger range of sizes to treat veins orother vessels elsewhere in the body.

[0084]FIGS. 28-31 depict another embodiment of the present invention inwhich a open frame 11, such as depicted in FIG. 28, is assembled into asquare frame (FIGS. 29-31) such the bends 12 are put under tension. Theresiliently tensioned bends 118 in the assembled device (as shown inFIGS. 29-31) result from the initial angle 109 formed in wire frame 11before being assembled into a closed circumference 62 (FIG. 28), beinggreater than the final angle 110. To form the embodiment of FIG. 1, forexample, the wire is wrapped around a pin to form the coil turns 14 withthe sides 13 generally lying about 90° with respect to one another. Theattachment mechanism 15 then secures and closes the frame 11 to form thefinal square shape. In the embodiments of FIGS. 28-31, the first angle109 is made approximately 150°, rather than 90°, which is the desiredfinal angle 110. While the wire is not under stress after the bends 12are initially formed, the bends 12 and sides 13 are stressed when thedevice 10 is constrained during assembly to form the four-sided,generally square shape. In particular reference to FIG. 30, the sides122,123 adjacent to a resiliently tensioned bend 118 becomes somewhatdeformed when the bend 12 is put under stress, generally assuming abowed shape between the adjacent bends. By creating this ‘roundedsquare’ with tensioned or stressed bends 118, the sides 13 of the frame11 are able to better conform to the rounded vessel wall 70 than would aside 13 that is initially straight prior to deployment. Additionally, byrounding the distal bends 116 of the valve legs 113, it may also reducethe potential for the valve legs 113 to cause trauma to the vessel 33 asthey continue to exert force thereupon.

[0085] An additional method of constraining the valve 43, or similartype device 10 (e.g., occluder, filter, stent, stent adaptor), isdepicted in FIG. 48 in which a circumferentially constraining mechanism125, is added to at least partially encircle the frame 11 while it is inboth the delivery configuration 37 (FIG. 6) and the deployedconfiguration 36 such that the device 10 is limited in its ability toradially expand. Once the device reaches its maximal radial expansion,the outward force the device 10 places on the vessel wall 70 iseliminated, thereby reducing potential damage thereto (e.g., from animproperly sized valve), such as tissue erosion possibly resulting ineventual perforation of the vessel 33. In the illustrative embodiment,the circumferentially constraining mechanism 125 comprises a suture thatis affixed to and completely encircles the frame 11 to limit the outwardexpansion of the valve legs 127,128. The sides 13 of the valve legs127,128 include an intermediate coil turn 126, also illustrated in FIG.39 fulfilling a different function, that provides an effectiveattachment point through which to feed and/or affix the suture restraint125. In the illustrative embodiment, the suture restraint 125 is in arelaxed state when the device 10 is loaded in the delivery system. Then,as the device 10 is deployed, it expands within the vessel 33 until itis constrained by the suture restraint 125 if the device 10 has beenproperly sized such that vessel 33 does not provide constraining forcessufficient to prevent the device 10 from fully expanding to itspredetermined maximum diameter. If the device is undersized for thediameter of the vessel, it may be subject to migration due toinsufficient expansion. The illustrative embodiment is merely exemplaryof the numerous available circumferentially constraining mechanisms 125.It is not necessary that the circumferentially constraining mechanism125 completely encircle the device 10. For example, short pieces ofsuture or another type of tethering mechanism, such as a section ofwebbing or other material, can be affixed between the sides of the valvelegs to limit their expansion, or the frame can include an integralcircumferentially constraining mechanism, such as an expandable strutformed as part of the frame. The strut would unfold as the frameradially expands and limits how far the sides of the valve leg to whichis attached, can spread apart relative to each other, thereby limitingthe outward radial force from the device against the vessel wall.

[0086] Another possibility is for circumferentially constrainingmechanism 125 to comprise a sleeve 162 of flexible material, such as SISaround the valve 43, as depicted in FIG. 50, which is of a diameterappropriate for deployment within the target vessel 33 (typically, beingslightly larger than the target vessel diameter) that allows the valveto anchor thereto. The sleeve 162 could be affixed to the frame 11 withsutures 50 or by some other means as the valve 43 is held in a collapsedcondition prior to loading the device 10, including the sleeve 162, intoa delivery system. The sleeve 162 enclosed the length of the valve 43,or the bends 12 and barbs 16 can be left uncovered, as shown. To reduceresiliency of the sleeve 162, tethers and other types ofcircumferentially constraining mechanism 125 can be used in combinationwith the sleeve 162 to limit radial expandability of the valve 43. Itshould be noted that if the circumferentially constraining mechanism 125itself is a resilient member, it will only serve to reduce the outwardforce of the device 10 against the vessel wall 70 until maximumexpansion is reached.

[0087]FIGS. 30-31 depict alternative methods of forming the frame 11 andattaching barbs thereto. In the embodiment shown in FIG. 30, attachmentmechanisms 15,85 and 84,86, per side rather than a single cannula asshown in previous embodiments, such as FIG. 29. Rather than placing theattachment mechanisms 15 at the point 87 where the respective ends 60,61of the wire frame 11 cross to form the square shape, two attachmentmechanisms 15,85 are placed on either side of the cross point 87. Havingan additional attachment mechanism 84,85,86 on a side 13 provides betterfixation of the frame with little additional metal and helps preventtwisting of the frame 11. On the opposite side which contains the doubleended barb 39, the double attachment mechanisms 84,86 arrangementprovides a similar function. In the embodiment of FIG. 31, threeattachment mechanisms 15,85,88 and 84,86,89, are used per side whichprovide better fixation of the frame 11 as well as serving as attachmentpoints for including supplemental barbs 90,91,92,93 to provide a moresecure anchoring of the device 10 to the vessel wall 70. Theillustrative barbs 16 are typically configured such that they extendonly a short distance (less than 1-2 mm) beyond the bends 12; however,the barbs 16 can be made virtually any practical length, such asextending them more than 1 cm beyond the bends 12 to aid in stabilizingthe device 10 upon deployment such that it does not shift laterally andend up being cockeyed within the vessel. To assist in this function, thebarbs can be shaped accordingly, rather than be limited to asubstantially straight configuration.

[0088] The present invention is not limited to a two-leaflet valve 43(or two-leg occluder or stent adaptor, etc.). FIGS. 35-40 depictmulti-leaflet valves 43 having three or four valve legs 113 and leaflets25. The addition of additional leaflets reduces the load produced by thefluid column upon each individual leaflet 25. This in turn, puts lessstress upon the sutures or attachment points of the covering 45, therebyallowing the valve 43 to function under higher pressures than wouldotherwise be possible. For example, these valves 43 could proveadvantageous for use on the arterial side, such as to augment pulmonaryvalves, or within the heart itself, where pressures exerted on theleaflets can be significantly higher than normally found on the venousside. FIG. 35 depicts a valve 43 which in the generally flattenedconfiguration 35, has a three legs 127,128,130 that lie approximately120° with respect to one another. The respective leaflets are arrangedsuch that the inner edges 111 thereof, define a triangular-shaped valveorifice 117. When the illustrative valve 43 is placed in the vessel 33for which it has been properly sized, as depicted in FIG. 37, theleaflets 78,79,119 are able to close against one another to seal thevalve. The concept of adding additional legs 113 to distribute the loadover a larger number of attachment points 50 (e.g., sutures) and addpositional stability to the device 10, can be applied to occluders andstent adaptors as well.

[0089] One method of forming the embodiment of FIG. 35, involvesconstructing a triangular-shaped frame 11, as shown in FIG. 36, thatincludes an intermediate coiled eyelet 132 formed at the midpoint ofeach of the three sides 13. A temporary constraining suture 121, such asthat shown in FIG. 38, is threaded through each of the intermediateeyelets 132, drawing them inward to form three additional bends133,134,135 forming three legs 127,128,130 of a desired shape (FIG. 35),depending how tightly the constraining suture 121 is drawn. At thispoint, the covering 45 is attached to the frame 11, either as threeseparate leaflets 78,79,119, or a single piece through which thetriangular-shaped valve orifice 117 is formed. After the covering 45 hasbeen secured to the frame 11, the constraining suture 121 is cut andremoved. As depicted, the barbs 16 are affixed to the triangular shapedframe of FIG. 36, two per side, such that they terminate on either sideof intermediate eyelet 132. Thus, when the intermediate eyelets 132 aredrawn inward to create six sides 13, each includes a barb 16.

[0090] The embodiment of FIGS. 38-40, which includes four legs127,128,130,131, is formed in a similar manner to that of the embodimentof FIGS. 35-37. The frame 11 is initially formed in a squareconfiguration (FIG. 39) with intermediately placed coiled eyelets 132 atthe midpoint of each side 13, dividing the side into a first and secondside portion 137,138. As depicted in FIG. 38, the temporary constrainingsuture 121 is used to draw the eyelets inward where they form the fouradditional bends 133,134,135,136 such that four valve legs127,128,130,131 are formed with the first and second sides portions137,138 becoming sides 13 of adjacent valve legs 127,128. Asquare-shaped valve orifice 117 is created when the four leaflets78,79,119,120 are attached to the legs 127,128,130,131 of frame 11. Oneshould appreciate that valves with more than four legs would be made ina similar manner to the embodiments above with a five-sided valve beingformed from a pentagon, a six-sided valve being formed from a hexagon,etc.

[0091] Delivery of the device 10 of the present invention can beaccomplished in a variety of ways. One method, depicted in FIG. 33,involves the use of a delivery system 103 similar to that used todeliver embolization coils. The delivery system 103 comprises an outermember 105, such as a cannula or catheter, and an coaxial inner member105 that includes a tethering tip 107, such as a notched cannula,adapted to receive a barb 17 extending from the frame 11. The tip 104 ofthe barb is configured such that it can positively engage with thetethering tip 107. This can be accomplished by adding a projection, suchas a secondary barb, hook, spine, etc. to the tip 104, or otherwiseenlarging the diameter thereof such that it can be releasably secured bythe tethering tip 107 until deployment. The coaxial inner member 106also includes an outer sheath 149 that retains and the locks the barbtip 104 within the tethering tip 107 until it is advanced or retractedby manipulation of a proximal handle (not shown) to expose the notch 150in the tethering tip, which releases the barb 17 and deploys the device10. The device 10 is preloaded within the outer member 105. The coaxialinner member 106 and attached device 10 are then advanced together fromthe outer member 106 at the target site. Further manipulation of theproximal handle, advances the tethering tip 107, which in thisparticular embodiment, includes a coiled spring 151, relative to theouter sheath 149. After the device 10 has been released from thetethering tip 107, the spring-activated handle is released and the outersheath 149 slides back over the tethering tip 107. The coaxial innermember 106 is withdrawn into the outer member 105 and the entiredelivery system 103 is removed from the patient. As shown in FIG. 33,the barb tip 104 extends just beyond the coil turn 14 of the frame 11 soas to have sufficient room to engage with the coaxial inner member 106.The barb tip 104 must be positioned to account for whether the device 10is to be placed using a femoral approach or a superior approach.

[0092] The illustrative delivery system 103 represents only one of manypossibilities. For example, the device 10 can be attached to a deliverydevice using screws, clips, magnets, or some other tethering mechanism,or can be deployed by applying electrical current, heat, or some othermeans to cause detachment with a carrying mechanism. As previouslydisclosed, rather than making the device 10 self-expanding, where it ispushed from some sort tubular device, it can be formed from a ductilematerial, mounted over a balloon or other inflatable or expandabledelivery mechanism, and deployed by expanding the device in that manner.

[0093] It is thus seen that the present invention includes deviceshaving a number of configurations with regard to the frame, covering,barbs, etc. Futhermore, it has been seen that the invention and can beformed in a variety of ways using a different types of medical gradematerials, and has utility to treat a wide range of medical problems.The embodiments contained herein should be considered merely exemplaryas one skilled in the medical arts would appreciate that furthermodifications would be possible that would be included within the spiritof the invention.

What is claimed is:
 1. An expandable implantable valve prosthesis,comprising: a support frame supporting one or more leaflets, eachleaflet comprising a biomaterial, the support frame and the one or moreleaflets together functional as a valve to restrict blood flow in afirst direction when implanted in the vascular vessel; and wherein thebiomaterial is folded over the support frame and attached to itself,thereby securing the one or more leaflets to the support frame.
 2. Theimplantable valve of claim 1, wherein a cross-linking agent provides theattachment of the biomaterial to itself.
 3. The implantable valve ofclaim 1, wherein an adhesive provides the attachment of the biomaterialto itself.
 4. The implantable valve of claim 1, wherein welding providesthe attachment of the biomaterial to itself.
 5. The implantable valve ofclaim 4, wherein a heat source provides the weld that attaches thebiomaterial to itself.
 6. The implantable valve of claim 1, wherein theapplication of pressure provides the attachment of the biomaterial toitself.
 7. An implantable valve prosthesis, comprising: a support framesupporting one or more leaflets, each comprising a biomaterial, the oneor more leaflets including a body, an inner edge, and an outer edge;wherein the support frame and the one or more leaflets togetherfunctional as a valve to restrict blood flow in a first direction whenimplanted in the vascular vessel; and wherein the leaflet outer edge isfolded over the support frame with the outer edge or portion adjacentthereto being attached to the leaflet body by a non-suturing method thatinclude at least one of the group consisting of cross-linking agents,adhesives, pressure welding, crimping, and heat welding, therebysecuring the one or more leaflets to the support frame.
 8. Theimplantable valve of claim 7, wherein the method includes heat to attachthe biomaterial to itself.
 9. The implantable valve of claim 7, whereinthe method includes pressure to attach the biomaterial to itself.
 10. Animplantable vascular valve, comprising: a support frame; one or moreleaflets comprised of biomaterial attached to the support frame andconfigured to function as a valve; and wherein the biomaterial iswrapped around the support frame and welded to itself, thereby securingthe one or more leaflets to the support frame.
 11. An implantablevascular valve, comprising: a support frame; one or more leafletscomprised of biomaterial attached to the support frame and configured tofunction as a valve; and wherein the biomaterial is wrapped around thesupport frame and affixed to itself using an adhesive, thereby securingthe one or more leaflets to the support frame.
 12. An implantablevascular valve, comprising: a support frame; one or more leafletscomprised of biomaterial attached to the support frame and configured tofunction as a valve; and wherein the biomaterial is wrapped around thesupport frame and affixed to itself using the application of pressure,thereby securing the one or more leaflets to the support frame.
 13. Anexpandable implantable vascular valve, comprising: a support framehaving a wall-engaging outer edge; one or more leaflets comprised ofbiomaterial attached to the support frame and configured to function asa valve; and wherein the outer wall-engaging edge of the support frameis enclosed by at two layers of the biomaterial attached to one anotherby a non-suturing method that include at least one of the groupconsisting of cross-linking agents, adhesives, pressure welding,crimping, and heat welding, thereby securing the one or more leaflets tothe support frame.